How Does A Whole House Fan Work? (*2020 Guide*)

Do you want to find out how whole house fans work?

At Home Inspector Secrets, we’ll give you the down and dirty on how whole house fans work — and if the purchase is worth the hassle.

In this article, you will discover…

  • Exactly how whole house fans work to cool down your home
  • How increasing your attic vents can double the performance of a house attic fan
  • How you can save up to 90% on your A/C costs by using a whole house fan
  • One little-known reason why people love whole house fans, known as “the breeze effect”
how does a whole house fan work

Let’s get started with this guide!

Will A Whole House Fan Cool Down My Home?

The answer to this question is that yes, whole house fans work very well at cooling homes, but only under certain conditions.

According to Kansas State University, a whole house fan is most effective when the exterior air is cooler than your home’s interior, and the outdoor air also has low humidity — more typical of drier climates.

Obviously, if the outdoor air is warmer than the home’s interior air, then the cooling effect will be almost non-existent…though the “breeze effect” may still be nice on the skin.

A whole house exhaust fan works by exhausting the stale and warm interior air to the outside through the attic vents such as the ridge, gable, and passive vents. The whole house fan will then pull in fresh outdoor air into your home to quickly cool the entire house.

The most common times to use a all house fan is during the early morning and in the evening because as the sun goes down, the air dramatically cools..

Some homeowners like to just turn on the whole house fan for 30 minutes or so in the evening, and this is enough to keep them cool for the entire night. Other users like to keep the whole house fan on during the entire night.

Leaving the whole house fan on all night will help keep the home cool for the next day, and it will delay the need for using the expensive air conditioner, or may even eliminate the need for it.

If you run the whole house fan during the entire night, you may want to put it on the low speed setting in order to minimize noise and energy usage.

Read Also: ​The Best Whole House Fans (Review)

How Do I Get The Most Performance Out Of A Whole House Attic Fan?

According to the U.S. Energy Department, the best way to improve the performance of a whole house fan is to increase your attic ventilation. Most attics will have a combination of soffit, ridge, and gable ventilation (as well as single unit passive vents).

This makes sense because a whole house fan is expelling the warmer interior air to the outside through the attic vents.And if there isn’t enough attic venting, then this greatly slows down the rate at which the air is moved to the outside.

Not enough attic venting will put strain on the fan, causing it to use more energy, and the cooling effect will take much longer.

This is why it would be better to have a less powerful whole house fan (a lower CFM rating) but with much more attic venting — compared to the opposite — a very powerful fan but with less attic vents.

In addition, installing more attic venting is relatively cheap compared to the cost and installation of a whole house fan.

Open Windows For A Whole House Fan To Work Properly

In addition to increasing your attic venting, it is important to open an adequate number of windows or doors. Whole house fans create a negative pressure on the interior of the home, while exerting a positive air pressure inside the attic.

You need enough intake air for a whole house fan just like for attic fans, except the intake air is through windows and doors.

If there isn’t enough openings for fresh outdoor air to be pulled into the home, then the whole house fan is going to work much harder, and won’t be nearly as effective.

Use Ceiling Fans For More Home Cooling

The U.S. Energy Department also recommends using ceiling fans together with a whole house fan in order to get the most cooling for your home.

Read Also: How To Use Whole House Fans

how does a whole house fan work (ventilation)

Is A Whole House Fan Faster Than A Traditional A/C?

The best whole house fans are significantly faster than a traditional air conditioner because an A/C system does not expel any of the warm interior air to the outside.

A whole house fan is similar to when you first enter a car on a very hot day. What is the first thing you do? You open the windows, and blast on the A/C. The A/C “pushes” out the hot air to the outside, and replaces it with cooler air.

With a traditional home A/C this process can take a while because it isn’t connected to the exterior.

How Much Can I Save With A Whole House Fan Installation?

The typical whole house fan is about 70-90% cheaper than a traditional split system air conditioner.

While an average 3 ton air conditioner may use up to 3500 watts, a whole house fan may use only 100 watts which is about 35 times less energy.

Read Also: Whole House Fans Vs. Attic Fans (What’s The Difference?)

Can I Use The Whole House Fan When It Is Warmer Outside?

Yes, you can still use a whole house fan when it is the same temperature as the outside or even warmer, and there are even other benefits besides cooling.

For one, using a whole house fan for a few minutes before you turn on your air conditioner will greatly speed up the cooling effect of your traditional A/C if you decide to use it. This works by expelling all of the hot air in your home which your A/C cannot do.

After you have expelled all of the warm interior air, then you can turn on the A/C and it will cool down the home much faster.

how does a whole house fan work

Are There Other Advantages Of A Whole House Ventilation Fan Besides Cooling?

A Nice Ventilation Benefit — The Breeze Effect

In additional to helping your A/C, if the outdoor air is the same temperature or even a little warmer, you can still benefit from the “breeze effect” of your whole house fan.

It would be similar to having an outdoor ceiling fan on a porch. Even though it isn’t pulling in cooler air, you will still feel cooler because of the breeze just by itself.

This phenomenon is known as evaporative cooling.

Remove Pollutants

Besides the breeze effect, another benefit of a whole house fan is that it removes pollutants from your home such as radon gas, formaldehyde, cooking fumes, and other harsh chemicals.

Especially with today’s modern homes, our houses are designed to be ultra air tight and energy efficiency.

The problem with a house being air tight is that it also tends to capture bad fumes and harsh chemicals. For some homeowners, this reason alone may be enough to invest in a whole house fan.

Read Also: How To Use A Whole House Fan

The Bottom Line — Do Whole House Fans Really Work?

In my opinion, as a licensed home inspector, is that whole house fans can be a great investment for your home, and definitely be worth the expense. However, it isn’t always a one-sized fits all solution. In dryer climates, whole house fans tend to be much more popular than in the humid northeast.

In addition, older model whole house fans can also be noisy, and much less efficient that newer whole house fan models such the Quiet Cool whole house fans. But there are even ways to make a whole house fan quieter such as by using rubber seals, and even building a platform above the ceiling joists.

Regardless, it’s a good idea to considering adding a whole house fan for your home comfort.

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Arie Van Tuijl

Arie Van Tuijl

Arie is the founder of Home Inspector Secrets, an online resource dedicated to helping owners and buyers understand homes. He is a licensed home inspector in two U.S states and also owns a residential and commercial inspection company.

About Home Inspector Secrets

Home Inspector Secrets is an online resource for owners, buyers, and sellers to understand all aspects of home ownership. We have detailed home guides, product reviews, inspection advice, buying tips, and much more.